The present invention relates to document handling system, and more particularly to a roller for reducing magnetic interference in a MICR read head.
Magnetic ink characters are characters or symbols which are printed on a document using magnetic ink. Documents containing magnetic ink characters are typically bank checks, deposit slips and other documents. Magnetic ink characters may be printed in a standardized format or font such as, for example, E13B or CMC7, and are typically located near an edge of a document.
Magnetic ink characters are read by a magnetic head as the head moves across the document or the document is caused to move past the head. The magnetic signals detected by the head are converted to electrical signals which are processed by a magnetic ink character recognition (MICR) system.
Document processing systems with a MICR capability can be affected by magnetic interference which slows or prevents magnetic ink characters from being read. Magnetic sources, such as, for example, electromagnetic coils, generate magnetic fields resulting in interference relative to the magnetic information stored in the magnetic ink portion of a document. These interference signals may arise from nearby equipment such as displays, scanners, the MICR processing system itself, or motors and other electromechanical devices that may be used to move documents along a transport path. Other devices located along the transport path, such as, for example, rollers including bearings, generate magnetic field interference which causes poor signal to noise ratio in the MICR read head. This problem is increased when roller bearings fail which causes high frequency noise in the MICR read head.
A need has thus arisen for a roller for use in a document transport system which reduces magnetic interference for proper operation of a magnetic read head.
In accordance with the present invention, a document transport system is provided wherein documents containing magnetized encoded indicia are to read by a magnetic ink character recognition read head as the documents are transported by rollers along a document transport path. The system includes a base plate disposed along the document transport path. A shaft is attached to the base plate and disposed generally perpendicular to the base plate. A hub member having a top surface, a bottom surface, an outer peripheral surface and a centrally disposed aperture receives the shaft. The hub member is supported on the base plate for rotation about the shaft. The hub member includes a slot spaced apart from and disposed between the centrally disposed aperture and the outer peripheral surface. A magnetic shield is attached to the base plate and is disposed within the hub member slot.